Easter eggs solution from CTF announcement from Bi.Zone

A few weeks before the start of registration at CTF, organized by BI.Zone , an announcement of this event was posted on various information portals.

If you look at the announcement , for example, on the site ZN2016, then you can notice some oddity in the formatting of the text.

An experienced eye will notice that words are separated by one or two spaces. This suggests that the message encoded information.

There are many codes that can encrypt information in this way, but only one fits: one space encodes '0', two - '1'. After decoding, it was possible to get a binary string:
')

That, after transferring to ASCII, gives 'promo.bi.zone' . This ends the first stage of the task.

When you go to the site, it turned out that it is not available. Upon further investigation, for example, nmap, it was possible to see that there are two ports open on the server - 22 (ssh) and 90 . At port 90 there is a large image with the BI.Zone logo.

Having examined it carefully, you can see the QR code at the bottom of the picture. This code contains the text 'Try to find me (; Father calls me ctfzone' . Obviously, you need to find someone with such a nickname in one of the popular services.

The phrase 'Father calls me' is a reference to the Telegram bot, which registers the bot, 'BotFather' . In Telegram you can find a bot with the nickname @ctfzone .

When you start communicating with the bot, you will learn that you need to solve several sudoku. Sudoku is solved in any way, for example, using the pythonsudoku module. After solving ten sudoku, the bot responds with the message: 'Post your flag on twitter with #ctfzone and mention @CtfZone: flag' .

By posting the appropriate tweet, you could get your prize.

The first to solve all the tasks received an invite to ZN2016, the rest will receive their prizes at the conference.